This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The two-photon laser-scanning microscope available in our facility is equipped with dual galvonometeric laser scanners with each of these scanners independently directing two beams from ultrafast lasers. Both scanners are under the control of custom software allowing for simultaneous photo-release of various caged compounds and two-photon imaging of associated signals as well as electrical recordings. The combination of excellent spatial resolution, tissue penetration and low phototoxicity allows the microscope to be used in a wide range of experiments.